To the Editor.—Dr Kerlikowske and colleagues1 unfortunately add to the prevailing confusion regarding the utility of mammographic screening in women 40 to 50 years of age by jumping to an unfounded conclusion at the end of their article.Their analysis indicates that screening between 40 and 50 years of age does not show a demonstrable improvement in mortality until women are followed up for 10 to 12 years. They propose that this is merely because after 10 years, women who are initially 40 to 50 years of age ineluctably become a 50- to 60-year-old age group, for which mammography is efficacious. In the body of the article they observe, "The findings suggest that it might be possible to wait to begin screening when women become 50 years old or menopausal, and achieve the same benefit in mortality reduction as beginning screening at 40 years of age." However, in